Insulated electric conductor



(No Model.)

J. D. BISHOP.

INSULATB'D ELECTRIC CONDUCTOR.

No. 449,400. Patented Mar. 31, 1891.

QN, JIS/.M55 ZLEA? Hap UNITED STATES PATENT OFFICE.

JAMES D. BISHOP, OF BROOKLYN, NFW YORK.

INSULATED ELECTRIC CONDUCTOR.

SPECIFICATION forming part of Letters Patent No. 449,400, dated March 31, 1891i Application filed September 22', 1890. Serial No. 365;722. (No model.)

the same.

This invention relates to insulating electric conductors.

Its object is to insure a high insulating power, low inductive capacity, cheapness of construction, and increased lightness and flexibility..

An ideal conductor or cable would be one in which the conductor was maintained throughout the Whole length equidistant from the protective sheathing by a material eifering a maximum electrical resistance and a minimum inductive capacity. Dry air possesses these qualities to a higher degree than any other known material and would be the ideal medium of separation of the conductor from the inclosing sheath or adjacent conductors, provided the conductor could be maintained throughout its length with an intervening layer or stratum of such air between it and its inelosing sheath. The nearer an insulated conductor approaches thisform the greater will be its advantages in a high resisting power to leakage and a lower inductive capacity, and it will also be of materially-de creased weight, of increased flexibility, and diminished cost.

It is the object of myinvention to surround the conductor as much as is practically possible with such a protective envelope of dry air, and yet maintain it in a fixed relation to its inclosing sheath.

The features of novelty of the invention Willbe hereinafter fully described in the specieation, and definitely indicated in the appended claims.

In carrying out my invention I apply au insulating material, preferably in strips, spirally around the conductor in such a manner that instead of overlapping on itself in successive eonvolntiens, asis common in the art,

air-spaces are established between the sides of the spiral by giving the thread of the spiral such a pitch that the edges of the strips cannot overlap, but will be separated by a Wide space. These strips may be laid upon one anotherin the same plane to several thicknesses, so that the thread may be as deep as desired, and vthus as great an airspace secured as the design of the cable requires. rlhis result may be accomplished by giving to the conductor such a rate of feed With reference to the Winding machinery that air-spaces of a desired Width will be left between the sides of the spiral strip. When a sucient thickness of a spirally-Wound material has been produced, the protective envelope or sheath is applied to the conductor, which is then complete. The insulating material or ribbon which I prefer to use in win din g the conductor is paper, both by reason of its lightness in Weight,its eheapness, and its high insulating power.

In the accompanying drawingsmhich illustrate the invention, Figure l is a sectional view of a portion of a conductor or cable constructed in accordance with my invention. Fig. 2 is a sectional View of a portion of the conductor in which a single spiral band of insulatin g material is Wound upon the conductor. Fig. 3 illustrates a method of closing the ends of the conductor, so to prevent the entrance of moisture to the airspiral; and Fig. a illustrates in enlarged viewa series of strips piled to the desired thickness which hold the conductor in fixed relation to its inclosing protective sheath.

A is the conductor.

B is a series of superposed strips of insulating material, preferably paper, Wound upon the conductor with a quick pitch, so as to leave at intervals in the length of the conn duetor Wide spaces C O.

The sheath D may be applied directly to the conductor after being Wound with the strip B, as shown in Fig. 2; or additional spirals of insulating material E F, reversely Wound, may be applied before the conductor is inclosed in its sheath, as shown in Fig. I.

The ends of the conductor are finished by completely surrounding them with the insulating material, as shown at G. This result `It is herebyfcertiecl that in Letters` Patent No. 449,400, granted March 31,1@91 upon the application ot' J ames D. Bishop', of Brooklyn, New York, for an improvenien inInsnlatecl Electric Oondnctors/7 an error appears in the printed specification reqil ing correction, as follows: In line 3, page 1, the Clause citizen of the United States, should read subject of the Queen Britain; and that the said Letters should be read with this correction therein that the sa of the case in the Patent Gfce.

me may conform to the record Signed, countersignerl, and sealed this [SEAL] 28th clay of April, Ar.V D. 1891.

GYRUS BUSSEY, t jg Assistant Secretary 0j' the Interior; Oountersigned: a

C. E. MITCHELL,

Commissioner 0j' Patents. 

